Paint application device

ABSTRACT

A paint application device, in particular suited for the application of water-dilutable paints, comprises a paint reservoir connected with a paint application device via a supply line. Further, a paint discharge device for returning excess paint from the area of the paint application device into paint reservoir is provided. For the adjustment or the maintenance of the viscosity of the paint, a humidification device is provided for increasing the air humidity in the area of the paint application device and/or in the paint reservoir.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 14/159,097, filed on Jan. 20, 2014, which claimspriority to German Patent Application No. DE 10 2013 201 487.2, filed onJan. 30, 2013, the disclosures of which are incorporated herein byreference.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

The disclosure relates to a paint application device, in particular forthe application of water-dilutable paints, where the term “paints”covers any kind of surface coating using in particular water-dilutablematerials.

2. Description of the Prior Art

For instance for the purpose of coating elongated work pieces, such asboards and the like, it is known to apply paints, lacquers or the likeon the surfaces by means of coating heads or spray heads, for example. Aspray head, suitable in particular for the application ofwater-dilutable paints or coatings, is described in EP 10 162 699.2, forexample. In this case, the paint is supplied into a chamber throughwhich the work piece to be coated is passed. Excess coating material iswithdrawn from the chamber, in which in particular a vacuum prevails,and is supplied to a paint reservoir. From the paint reservoir, thepaint is supplied to the spray head again by a pump or the like.Although this is a substantially closed circuit, it cannot be avoidedthat a part of the solvent contained in the paint, such as water,evaporates thereby causing a change in the viscosity of the paint. Owingto this increase in viscosity, the paint becomes more viscous so that auniform spraying of the paint in the spray head, and thus in particularan application of thin layers of paint and/or of exact applicationquantities, is no longer reliably ensured. Further, a clogging of thespray head and the like can occur. For this purpose it is known tosupply a solvent to the paint reservoir by opening a valve. This is alsothe case with highly viscous paints. This is very troublesome anddifficult, especially with water-dilutable paints, since the water oftenremains on the surface of the paint and mixing or stirring it into thesame is troublesome.

SUMMARY OF THE DISCLOSURE

It is an object of the disclosure to provide a paint application devicesuited in particular for water-dilutable paints, with which theviscosity of a paint can be changed or can be maintained despite achange in a simple manner. Further, it is an object of the disclosure toprovide a corresponding method.

The paint application device of the present disclosure, which issuitable in particular for working with water-dilutable paints, lacquersand coating agents, comprises a paint reservoir. The paint reservoir isconnected with a paint application device via a supply line, the devicecomprising a spray head or the like, for example. Here, paintapplication devices such as described in EP 10 162 699.2, for example,are suitable. Further, a paint discharge device for the discharge ofexcess paint from the area of the paint application device to the paintreservoir is provided. The paint discharge device may comprise a pump orsuction means, for example, wherein, in particular in the preferred useof a suction device, a vacuum is generated in a coating chamber of thepaint application device. According to the disclosure, further, ahumidification device is provided to increase air humidity in the areaof the paint application device and/or in the paint reservoir. Via sucha humidification device, the paint circuit is supplied with water vapor,for example. Of course, another solvent than water in the form of vaporcan be supplied. Such a supply of a solvent such as water, as a solventvapor is advantageous in that it is absorbed more easily by the paint sothat the viscosity of the paint can thereby be maintained or changed ina simple manner. No stirring in of the solvent in the paint reservoir isrequired.

According to the disclosure the humidification device can be provided inthe area of the paint application device. If, for example, the paintapplication device is a spray gun, the area in which the humidificationdevice is provided encompasses the area in which the spray mist isproduced by the spray gun. In particular this ensures that the solventvapor can be introduced into the spray mist to a sufficient degree.However, if the paint application device is a coating chamber, forexample, the humidification device is arranged within the chamber,preferably, however, in the vicinity of the spray heads. In any case,the arrangement of the humidification device in the area of the paintapplication device ensures that the solvent vapor introduced mixes withthe spray mist produced.

The paint application device may be one or a plurality of spray guns,for example, with which the water-dilutable paint, lacquer or the likeis applied onto a work piece. Here, instead of suctioning or pumping,the paint discharge device may effect a draining of excess paint, forexample via inclined, possibly cooled plates. Further, the paintdischarge device may be a plate on which excess paint deposits andaccumulates, with the paint being removed from the plate using a wiperor the like, for example. According to the disclosure, such a paintapplication device, as well as such a paint discharge device is alsoprovided with a humidification device in the area of the paintapplication device or in a paint reservoir for the purpose of increasingthe air humidity.

By means of the paint application device designed according to thedisclosure it is possible to very exactly define or adjust the amount ofpaint applied. Thus, short drying times or short drying distances can berealized. Moreover, the present paint application device has thedecisive advantage that the viscosity can be controlled very exactly.Thereby, it is possible to increase the proportion of solids in thepaint or the lacquer or in another coating agent. This, in turn, resultsin a shortening of the drying times or drying distances.

In order to be able to control the adjustment of the supplied amount orthe saturation of the solvent vapor as accurately as possible, aviscosity gage is preferably provided, the viscosity gage preferablybeing arranged in the supply line to the paint application device.Depending on the measured viscosity, the humidification device, and thusthe amount of solvent vapor supplied, can be controlled in particular bymeans of a control device.

In a particularly preferred embodiment the present paint applicationdevice preferably comprises a cooling device. Preferably, the coolingdevice is arranged downstream of the paint application device, seen inthe flow direction. Thus, the cooling device cools the mixture ofsolvent vapor introduced via the humidification device and excess paintwithdrawn from the application device. In this context, it isparticularly preferred that the cooling device cools a surface where themixture of excess paint and solvent vapor condenses. A particularlysuitable cooling surface is a surface in the paint reservoir, such as awall surface of the paint reservoir. In a particularly preferredembodiment, the control device preferably provided thus controls boththe humidification device and the cooling device in dependence on theviscosity measured by the viscosity gage. The control device allows thecontrol of both the amount of solvent vapor supplied and of thetemperature of the cooling surface.

According to the present method for adjusting the viscosity of inparticular water-dilutable paints and the like, the paint viscosity ismeasured. In an area in which the paint is applied onto a work piece,solvent vapor is supplied. As an alternative or in addition, solventvapor can be supplied in an area in which the paint is provided, inparticular in the paint reservoir. Preferably, the solvent vapor iswater vapor, while it is also possible to provide vapor of anothersolvent. According to the disclosure, the humidity is adjusted via theamount or saturation of the introduced solvent vapor in dependence onthe measured viscosity. Due to the supply of solvent vapor as providedby the disclosure, the viscosity of the paint can be adjusted in asimple manner even without providing stirring devices. The humidity isdefined by the saturation of the solvent vapor, in particular the watervapor.

In a particularly preferred development of the present method, thesolvent vapor supplied is preferably cooled. This cooling, effected inparticular via a cooling plate, causes the solvent vapor or a mixture ofexcess paint and the solvent vapor to condense. Thereby, the solvent isintroduced into the paint in a simple manner.

It is preferred to supply solvent vapor when a predetermined viscosityvalue is exceeded. Therefore, it is particularly preferred to not onlycontrol the humidity via the amount of the solvent vapor introduced orthe saturation thereof, but to also control the temperature of a coolingdevice, both as a function of the viscosity measured. In this context itis possible that the humidity or the amount of the solvent vaporsupplied can be changed only in a step-wise manner, for example, becausea finer adjustment is made through the temperature.

It is particularly preferred to use the paint application device of thepresent disclosure for the implementation of the method of the presentdisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present disclosure, enabling oneof ordinary skill in the art to carry out the disclosure, is set forthin greater detail in the following description, including reference tothe accompanying drawing in which

FIG. 1 is a simplified schematical illustration of a first embodiment ofthe paint application device of the present disclosure,

FIG. 2 is a simplified schematical illustration of a second embodimentof the paint application device of the present disclosure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The drawing figures are intended to illustrate the general manner ofconstruction and are not necessarily to scale. In the detaileddescription and in the drawing figures, specific illustrative examplesare shown and herein described in detail. It should be understood,however, that the drawing figures and detailed description are notintended to limit the disclosure to the particular form disclosed, butare merely illustrative and intended to teach one of ordinary skill howto make and/or use the disclosure claimed herein.

A paint reservoir 10 holds a paint 12, in particular a water-dilutablepaint. The paint reservoir 10 is connected with a pump via a line 14 andthe pump is connected with a paint application device 18 via a line 16.The paint application device 18 may comprise a spray head, for example.A work piece 20 to be coated or a work piece 20 to be passed through achamber of the paint application device 18 is arranged in the paintapplication device 18. Excess paint is discharged from the area of thepaint application device 18 via a line 22 and is returned to the paintreservoir 10. The discharge of excess paint from the area of the paintapplication device 18 can be effected by suctioning, for example. Forthis purpose a suction device 24 is connected with the paint reservoir10. Excess material is drawn off via the suction device 24, wherein acertain vacuum is possibly generated in a chamber of the paintapplication device 18.

In the embodiment illustrated, a viscosity gage 26 is arranged in thesupply line 16 between a pump 25 and the paint application device 18. Acontrol device 28 is electrically connected with the viscosity gage 26.Further, a humidification device 30 is electrically connected with thecontrol device 28 and is thus adapted to be controlled by the controldevice 28. In the embodiment illustrated, the humidification device 30is connected with the paint application device 10 and serves to supplysolvent vapor, specifically water vapor, via a line 32 to the area ofpaint application and in particular to the area in which excess paint isdrawn off. Thus, a mixture of excess paint and vapor is supplied to thepaint reservoir 10 via the line 22.

Further, the paint application device of the present disclosurecomprises a cooling circuit. By means of a cooling device 34, comprisingin particular a pump, a coolant such as water can be provided in acooling jacket 36 surrounding the paint reservoir 10. The cooling deviceeffects a cooling of an inner wall 38 of the paint reservoir 10. Themixture of vapor and excess paint reaching the paint reservoir 10 viathe line 22 is condensed at the cooled wall 38. Specifically thecondensed water vapor flows downward along the inner wall 38 and thusmixes well with the paint 12 present in the paint reservoir 10 so thatthe viscosity of the paint 12 is changed.

The cooling device 34 is also connected with the control 28. For acontrol of the paint application device of the present disclosure, thecontrol device performs a control of the temperature of the coolantand/or a control of the vapor amount supplied, both controls being madein dependence on the viscosity measured.

FIG. 2 shows a second embodiment wherein same parts are denoted by samereference signs. In the second embodiment the humidification device 30is connected to the paint reservoir 10.

All references cited herein are incorporated by reference to the fullextent to which the incorporation is not inconsistent with the expressteachings herein.

Although the disclosure has been described and illustrated withreference to specific illustrative embodiments thereof, it is notintended that the disclosure be limited to those illustrativeembodiments. Those skilled in the art will recognize that variations andmodifications can be made without departing from the true scope of thedisclosure as defined by the claims that follow. It is thereforeintended to include within the disclosure all such variations andmodifications as fall within the scope of the appended claims andequivalents thereof.

What is claimed is:
 1. Paint application device, in particular for theapplication of water-dilutable paints, comprising a paint reservoirconnected with a paint application device via a supply line, a paintdischarge device for returning excess paint from the area of the paintapplication device into paint reservoir, and a humidification device forincreasing the air humidity in the area of the paint application deviceand/or in the paint reservoir.
 2. Paint application device of claim 1,wherein the humidification device produces solvent vapor and introducesthe same into the areas of the paint application device and/or the paintreservoir.
 3. Paint application device of claim 1, further comprising aviscosity gage arranged in particular in the supply line.
 4. Paintapplication device of claim 3, further comprising a control device forcontrolling the humidification device, in particular for controlling thehumidity or the supplied amount of solvent in dependence on theviscosity measured, the control device being connected with theviscosity gage and the humidification device.
 5. Paint applicationdevice of claim 1, further comprising a cooling device arrangeddownstream of the paint application device in the flow direction. 6.Paint application device of claim 1, wherein the cooling device cools awall surface of the paint reservoir such that the solvent vaporcondenses thereon.
 7. Paint application device of claim 1, wherein thepaint discharge device comprises a suctioning device preferablyconnected with the paint reservoir.